1. Field of the Invention
The present invention relates to a method of manufacturing a polarizing eyeglass lens functioning to absorb or transmit light of a specific direction of polarization for the purpose of blocking light such as reflected light having a specific direction of polarization outdoors or the like.
2. Discussion of the Background
A variety of polarizing elements that pass or block only those components of incident light that are polarized in specific directions have come into use. For example, in optical pickups, there are glass elements that comprise multilayered films and diffraction gratings comprised of organic birefringent materials. Dichroic polarizing elements are employed in display devices such as liquid-crystal displays (LCDs) to increase contrast. They are manufactured by the method of tinting a film with a dichroic material such as iodine, crosslinking the film with a crosslinking agent, and uniaxially extending the film.
Further, polarizing elements can be manufactured by the method of coating a dichroic dye on an orientation layer on a substrate. This method utilizes the fact that water-soluble dichroic dyes exhibit liquid crystal properties based on concentration when dissolved in an aqueous solvent. When a coating material containing dichroic dyes exhibiting liquid crystal properties is coated on an orientation layer, uniform orientation of the liquid crystals is achieved and the dichroic dye in the coating film is uniaxially oriented. A thin film containing uniaxially oriented dichroic dye can be used as a polarizing element to achieve a polarizing function.
As an example of a method of manufacturing a polarizing element employing an orientation layer, WO2006/081006, which is expressly incorporated herein by reference in its entirety, discloses providing an orientation layer in the form of an inorganic intermediate layer between a transparent substrate and a polarizing layer in a polarizing product having a polarizing layer and a protective layer on the surface of a transparent substrate. WO2006/081006 describes that the inorganic intermediate layer functions to strengthen adhesion between the polarizing layer and the substrate, and that silica (SiO2) is suitable as a material for forming the inorganic intermediate layer.
Polarizing elements are used in manufactured products in addition to the above electronic devices and the like. For example, US2008/0252846A1 and Family member U.S. Pat. No. 7,597,442, which are expressly incorporated herein by reference in their entirety, propose a polarizing eyeglass lens incorporating a polarizing filter.
A description of polarization will be given. Based on Brewster's law, light reflecting off of a flat surface is known to contain a large s-polarization component in a direction of polarization perpendicular to the plane of incidence (the plane containing the normal to the position of incidence and the direction of incidence). Accordingly, when natural light reflects off of the vertical reflective surface of a building, most of the light that reflects is polarized in a direction that is perpendicular to the plane of incidence, that is, polarized in a direction parallel to the surface of the building, and spreads out. In US2008/0252846A1, the lens is divided into several zones and a polarizing filter with a different direction of polarization axis is provided in each zone to protect the eye of the wearer of the lens from the glare of reflected light. US2008/0252846A1 also discloses a method of manufacturing a polarizing lens comprising a customizing step of distinguishing between a type of lens wearer who moves the eyes themselves while exploring the environment and a type of lens wearer who moves his head, and varying the size of the zones on that basis.
The polarizing lens that is proposed in US2008/0252846A1 envisions vertically polarized light entering the lens from a direction precisely horizontal to the user, and horizontally polarized light entering from above. However, light becomes vertically polarized when it reflects off of the lateral surfaces of buildings and the like when the sun is low, such as at dawn and dusk. Horizontally polarized light from above strikes the wearer when the wearer and the position of the sun are aligned in a direction that is perpendicular to the surface of reflection.
Such conditions are for the most part special conditions. In the course of a day, natural sunlight mostly shines down on the surface of the earth from diagonally above the wearer (including both front and rear). Accordingly, when such light reflects off of building glass, panels, and the like, most of the reflected light enters the lens from diagonally above. That is, most of the reflected light that enters an eyeglass lens is light that has been polarized in diagonal directions that are different from the reference line direction (horizontal direction) and the meridian direction of the lens.
Thus, the polarizing lens of US2008/0252846A1 is incapable of fully blocking diagonally polarized light that enters from such diagonal directions. Most such light ends up being passed. Further, the daily living environment is comprised not just of smooth reflective surfaces such as building glass and panels, but also of the curved, glossy surfaces of vehicles and the like. The polarizing lens of US2008/0252846A1 cannot block the light containing complex directions of polarization that is reflected off of such surfaces.
When the directions of polarization axes are varied in each zone, the directions of polarization of the light that can be blocked are limited, numerous variations must be prepared based on use by the wearer, and difficulty is to be anticipated in responding to the needs of customers. Further, it is inconvenient for the wearer to carry all of these variations around with him and change out the lenses as needed. Thus, this is not a desirable polarizing lens.